xwm: Use Pango to draw title string if available

If Weston is built with Pango, use it to render the title for
X11 applications and Weston toy toolkit clients. It allows us
to ellipsize the title when there isn't enough space to show the
whole string.

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

Makefile.am

@@ -1138,12 +1138,14 @@ libshared_cairo_la_CFLAGS =			\
 	$(COMPOSITOR_CFLAGS)			\
 	$(PIXMAN_CFLAGS)			\
 	$(CAIRO_CFLAGS)				\
+	$(PANGO_CFLAGS)				\
 	$(PNG_CFLAGS)				\
 	$(WEBP_CFLAGS)
 
 libshared_cairo_la_LIBADD =			\
 	$(PIXMAN_LIBS)				\
 	$(CAIRO_LIBS)				\
+	$(PANGO_LIBS)				\
 	$(PNG_LIBS)				\
 	$(WEBP_LIBS)				\
 	$(JPEG_LIBS)

configure.ac

@@ -448,6 +448,9 @@ if test x$enable_weston_launch = xyes; then
 fi
 
 AM_CONDITIONAL(HAVE_PANGO, test "x$have_pango" = "xyes")
+if test "x$have_pango" = "xyes"; then
+  AC_DEFINE([HAVE_PANGO], [1], [Have pango])]
+fi
 
 AM_CONDITIONAL(HAVE_CAIRO_GLESV2,
 	       [test "x$have_cairo_egl" = "xyes" -a "x$cairo_modules" = "xcairo-glesv2" -a "x$enable_egl" = "xyes"])

shared/cairo-util.c

@@ -39,6 +39,10 @@
 #include "image-loader.h"
 #include "config-parser.h"
 
+#ifdef HAVE_PANGO
+#include <pango/pangocairo.h>
+#endif
+
 void
 surface_flush_device(cairo_surface_t *surface)
 {
@@ -451,14 +455,42 @@ theme_destroy(struct theme *t)
 	free(t);
 }
 
+#ifdef HAVE_PANGO
+static PangoLayout *
+create_layout(cairo_t *cr, const char *title)
+{
+	PangoLayout *layout;
+	PangoFontDescription *desc;
+
+	layout = pango_cairo_create_layout(cr);
+	pango_layout_set_text(layout, title, -1);
+	desc = pango_font_description_from_string("Sans Bold 10");
+	pango_layout_set_font_description(layout, desc);
+	pango_font_description_free(desc);
+	pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
+	pango_layout_set_alignment(layout, PANGO_ALIGN_LEFT);
+	pango_layout_set_auto_dir (layout, FALSE);
+	pango_layout_set_single_paragraph_mode (layout, TRUE);
+	pango_layout_set_width (layout, -1);
+
+	return layout;
+}
+#endif
+
+#ifdef HAVE_PANGO
+#define SHOW_TEXT(cr) \
+	pango_cairo_show_layout(cr, title_layout)
+#else
+#define SHOW_TEXT(cr) \
+	cairo_show_text(cr, title)
+#endif
+
 void
 theme_render_frame(struct theme *t,
 		   cairo_t *cr, int width, int height,
 		   const char *title, cairo_rectangle_int_t *title_rect,
 		   struct wl_list *buttons, uint32_t flags)
 {
-	cairo_text_extents_t extents;
-	cairo_font_extents_t font_extents;
 	cairo_surface_t *source;
 	int x, y, margin, top_margin;
 	int text_width, text_height;
@@ -497,6 +529,23 @@ theme_render_frame(struct theme *t,
 				 title_rect->width, title_rect->height);
 		cairo_clip(cr);
 		cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
+
+#ifdef HAVE_PANGO
+		PangoLayout *title_layout;
+		PangoRectangle logical;
+
+		title_layout = create_layout(cr, title);
+
+		pango_layout_get_pixel_extents (title_layout, NULL, &logical);
+		text_width = MIN(title_rect->width, logical.width);
+		text_height = logical.height;
+		if (text_width < logical.width)
+		  pango_layout_set_width (title_layout, text_width * PANGO_SCALE);
+		
+#else
+		cairo_text_extents_t extents;
+		cairo_font_extents_t font_extents;
+
 		cairo_select_font_face(cr, "sans",
 				       CAIRO_FONT_SLANT_NORMAL,
 				       CAIRO_FONT_WEIGHT_BOLD);
@@ -505,6 +554,7 @@ theme_render_frame(struct theme *t,
 		cairo_font_extents (cr, &font_extents);
 		text_width = extents.width;
 		text_height = font_extents.descent - font_extents.ascent;
+#endif
 
 		x = (width - text_width) / 2;
 		y = margin + (t->titlebar_height - text_height) / 2;
@@ -516,14 +566,14 @@ theme_render_frame(struct theme *t,
 		if (flags & THEME_FRAME_ACTIVE) {
 			cairo_move_to(cr, x + 1, y  + 1);
 			cairo_set_source_rgb(cr, 1, 1, 1);
-			cairo_show_text(cr, title);
+			SHOW_TEXT(cr);
 			cairo_move_to(cr, x, y);
 			cairo_set_source_rgb(cr, 0, 0, 0);
-			cairo_show_text(cr, title);
+			SHOW_TEXT(cr);
 		} else {
 			cairo_move_to(cr, x, y);
 			cairo_set_source_rgb(cr, 0.4, 0.4, 0.4);
-			cairo_show_text(cr, title);
+			SHOW_TEXT(cr);
 		}
 	}
 }